Long Term Evolution (LTE) dual connectivity is a feature wherein a user equipment (UE) is simultaneously connected to and provided with radio resources by two different network nodes: by a Master evolved Node B (MeNB) and by a secondary eNB (SeNB). This possibility for the UE to connect to two network nodes gives several advantages such as, for instance, increased data rate, increased network capacity and improved spectrum utilization.
There are different scenarios for the LTE dual connectivity feature, in view of control plane architecture as well as user plane architecture. For instance, the user traffic may be split at a core network level (e.g. in a serving gateway, S-GW) or at a radio network level (e.g. in the MeNB). Splitting in the S-GW entails disadvantages such as security being affected as ciphering is required both at the MeNB and the SeNB, while splitting at MeNB level has disadvantages such as all dual connectivity traffic having to be routed, processed and buffered in the MeNB. In the latter scenario flow control is also required between the MeNB and the SeNB.
From the above it is clear that there are many issues that need to be considered when implementing and also improving dual connectivity features.